This invention relates to encryption, and more particularly, to identity-based encryption schemes for securely distributing data.
It has become common to store content such as songs and video in digital form. Cryptographic techniques may be used to help secure such content from unauthorized use.
A number of cryptographic techniques are available for use in encrypting data. For example, symmetric key techniques have been extensively used. With symmetric key arrangements, a first party encrypts data for a second party using a symmetric key. The second party decrypts the encrypted data using the same symmetric key. Symmetric-key systems require that the symmetric key be exchanged between the parties involved in a secure manner.
With public-key cryptographic systems such as the RSA cryptographic system, two types of keys are used—public keys and private keys. Data for a given party may be encrypted using the unique public key of that party. Each party has a corresponding private key that is used to decrypt the encrypted data.
Identity-based encryption schemes have also been proposed. Such identity-based encryption schemes may use public parameters to encrypt data. These schemes are said to be “identity based,” because user-specific identity information such as a particular user's email address is used as one of the inputs to the encryption algorithm. Each user has a unique private key based on the user's identity for decrypting encrypted data. With this type of scheme, a single set of public parameters (used during the encryption and decryption processes) may be shared by many users.